1. Field of Invention
The present invention relates to a method and a system for controlling fuel injection for vehicles. More particularly, the present invention relates to a method and a system for controlling fuel injection for vehicles which control fuel injection amount according to change in kinetic energy of the vehicle or performs fuel cut control so as to improve fuel economy.
2. Description of Related Art
Recently, exhaust regulations and fuel mileage regulations have been strengthened in each country in order to overcome global warming and oil resource depletion. In order to enhance fuel economy, it is required for driving components such as power trains to be improved in hardware aspect and fuel cut control and idle stop and go control have been developed in software aspect.
The fuel cut control is stop supplying fuel to an engine under fuel cut condition. That is, enhancement of fuel economy is promoted by making the vehicle run by inertial force.
According to a conventional fuel cut condition, only engine control aspect such as intake amount, throttle valve opening, engine speed, time for reentering, and so on is considered. Such fuel cut control may be preferable in some aspect such as engine and exhaust controls, but may deteriorate fuel economy at a special driving mode.
That is, since the fuel cut control is performed when predetermined fuel cut condition is satisfied regardless change in kinetic energy of the vehicle, fuel cut control may be performed at a region where fuel cut is unnecessary. At this time, more fuel may be used for restoring the kinetic energy of the vehicle reduced by the fuel cut.
FIG. 5 is a graph illustrating vehicle speed and integrated fuel amount at some cases.
In FIG. 5, a solid line is a graph illustrating change in the vehicle speed and the integrated fuel amount at case 1, a dotted line is a graph illustrating the change in the vehicle speed and the integrated fuel amount at case 2, and a one-point chain line is a graph illustrating the change in the vehicle speed and the integrated fuel amount at case 3.
In addition, the case 1 is a case where an engine and a driving system are not connected and the engine is maintained at an idle state, the case 2 is a case where the vehicle is naturally decelerated without the fuel cut in a state that the engine and the driving system are connected, and the case 3 is a case where the fuel cut is performed in a state that the engine and the driving system are connected.
As shown in FIG. 4, fuel amount for running the same distance is as follows.case 1<case 2<case 3
That is, actual fuel economy may be further improved when the fuel cut is not performed, rather than when the fuel cut is performed in a state that the driving system is connected.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.